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* slob: record page flag overlays explicitlyAndy Whitcroft2008-07-241-0/+7
| | | | | | | | | | | | | | | | | | SLOB reuses two page bits for internal purposes, it overlays PG_active and PG_private. This is hidden away in slob.c. Document these overlays explicitly in the main page-flags enum along with all the others. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* slub: record page flag overlays explicitlyAndy Whitcroft2008-07-241-0/+7
| | | | | | | | | | | | | | | | | | SLUB reuses two page bits for internal purposes, it overlays PG_active and PG_error. This is hidden away in slub.c. Document these overlays explicitly in the main page-flags enum along with all the others. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page-flags: record page flag overlays explicitlyAndy Whitcroft2008-07-241-4/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the recent page flag reorganisation we have a single enum which defines the valid page flags and their values, nice and clear. However there are a number of bits which are overloaded by different subsystems. Firstly there is PG_owner_priv_1 which is used by filesystems and by XEN. Secondly both SLOB and SLUB use a couple of extra page bits to manage internal state for pages they own; both overlay other bits. All of these "aliases" are scattered about the source making it very hard for a reader to know if the bits are safe to rely on in all contexts; confusion here is bad. As we now have a single place where the bits are clearly assigned it makes sense to clarify the reuse of bits by making the aliases explicit and visible with the original bit assignments. This patch creates explicit aliases within the enum itself for the overloaded bits, creates standard bit accessors PageFoo etc. and uses those throughout. This version pulls the bit manipulation out to standard named page bit accessors as suggested by Christoph, it retains the explicit mapping to the overlayed bits. A fusion of both ideas. This has been SLUB and SLOB have been compile tested on x86_64 only, and SLUB boot tested. If people feel this is worth doing then I can run a fuller set of testing. This patch: Some page flags are used for more than one purpose, for example PG_owner_priv_1. Currently there are individual accessors for each user, each built using the common flag name far away from the bit definitions. This makes it hard to see all possible uses of these bits. Now that we have a single enum to generate the bit orders it makes sense to express overlays in the same place. So create per use aliases for this bit in the main page-flags enum and use those in the accessors. [akpm@linux-foundation.org: fix xen] Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'linus' into x86/xenIngo Molnar2008-06-161-0/+24
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| * mm: Minor clean-up of page flags in mm/page_alloc.cRuss Anderson2008-06-091-0/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | Minor source code cleanup of page flags in mm/page_alloc.c. Move the definition of the groups of bits to page-flags.h. The purpose of this clean up is that the next patch will conditionally add a page flag to the groups. Doing that in a header file is cleaner than adding #ifdefs to the C code. Signed-off-by: Russ Anderson <rja@sgi.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | xen: implement save/restoreJeremy Fitzhardinge2008-05-271-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements Xen save/restore and migration. Saving is triggered via xenbus, which is polled in drivers/xen/manage.c. When a suspend request comes in, the kernel prepares itself for saving by: 1 - Freeze all processes. This is primarily to prevent any partially-completed pagetable updates from confusing the suspend process. If CONFIG_PREEMPT isn't defined, then this isn't necessary. 2 - Suspend xenbus and other devices 3 - Stop_machine, to make sure all the other vcpus are quiescent. The Xen tools require the domain to run its save off vcpu0. 4 - Within the stop_machine state, it pins any unpinned pgds (under construction or destruction), performs canonicalizes various other pieces of state (mostly converting mfns to pfns), and finally 5 - Suspend the domain Restore reverses the steps used to save the domain, ending when all the frozen processes are thawed. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* PAGEFLAGS_EXTENDED and separate page flags for Head and TailChristoph Lameter2008-04-281-0/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Having separate page flags for the head and the tail of a compound page allows the compiler to use bitops instead of operations on a word to check for a tail page. That is f.e. important for virt_to_head_page() which is used in various critical code paths (kfree for example): Code for PageTail(page) Before: mov (%rdi),%rdx page->flags mov %rdx,%rax 3 bytes and $0x12000,%eax 5 bytes cmp $0x12000,%rax 6 bytes je 897 <kfree+0xa7> After: mov (%rdi),%rax test $0x40,%ah (3 bytes) jne 887 <kfree+0x97> So we go from 14 bytes to 3 bytes and from 3 instructions to one. From the use of 2 registers we go to none. We can only use page flags for this if we have page flags available. This patch introduces CONFIG_PAGEFLAGS_EXTENDED that is set if pageflags are not scarce due to SPARSEMEM using page flags for its sectionid on 32 bit NUMA platforms. Additional page flag definitions can be added to the CONFIG_PAGEFLAGS_EXTENDED section in page-flags.h if the functionality depends on PAGEFLAGS_EXTENDED or if more page flag overlapping tricks are used for the !PAGEFLAGS_EXTENDED fallback (the upcoming virtual compound patch may hook in here and Rik's/Lee's additional page flags to solve the reclaim issues could also be added there [hint... hint... where are these patchsets?]). Avoiding the overlaying of Pg_reclaim also clears the way for possible use of compound pages for the pagecache or on the LRU. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page flags: add PAGEFLAGS_FALSE for flags that are always falseChristoph Lameter2008-04-281-12/+7
| | | | | | | | | Turns out that there are a number of times that a flag is simply always returning 0. Define a macro for that. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page flags: handle PG_uncached like all other flagsChristoph Lameter2008-04-281-11/+8
| | | | | | | | | | | | Remove the special setup for PG_uncached and simply make it part of the enum. The page flag will only be allocated when the kernel build includes the uncached allocator. Acked-by: Dean Nelson <dcn@sgi.com> Cc: Jes Sorensen <jes@trained-monkey.org> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: eliminate PG_xxx aliasesChristoph Lameter2008-04-281-8/+4
| | | | | | | | | | | | | | | Remove aliases of PG_xxx. We can easily drop those now and alias by specifying the PG_xxx flag in the macro that generates the functions. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: use proper page flag functions in XenChristoph Lameter2008-04-281-1/+1
| | | | | | | | | | | | | | | Xen uses bitops to manipulate page flags. Make it use proper page flag functions. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: convert to the use of new macrosChristoph Lameter2008-04-281-127/+68
| | | | | | | | | | | | | | | | | Replace explicit definitions of page flags through the use of macros. Significantly reduces the size of the definitions and removes a lot of opportunity for errors. Additonal page flags can typically be generated with a single line. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: introduce macros to generate page flag functionsChristoph Lameter2008-04-281-0/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce a set of macros that generate functions to handle page flags. A page flag function group typically starts with either SETPAGEFLAG(<part of function name>,<part of PG_ flagname>) to create a set of page flag operations that are atomic. Or __SETPAGEFLAG(<part of function name>,<part of PG_ flagname) to create a set of page flag operations that are not atomic. Then additional operations can be added using the following macros TESTSCFLAG Create additional atomic test-and-set and test-and-clear functions TESTSETFLAG Create additional test and set function TESTCLEARFLAG Create additional test and clear function SETPAGEFLAG Create additional atomic set function CLEARPAGEFLAG Create additional atomic clear function __TESTPAGEFLAG Create additional non atomic set function __SETPAGEFLAG Create additional non atomic clear function Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: get rid of FLAGS_RESERVEDChristoph Lameter2008-04-281-7/+12
| | | | | | | | | | | | | | | | | | | | | | NR_PAGEFLAGS specifies the number of page flags we are using. From that we can calculate the number of bits leftover that can be used for zone, node (and maybe the sections id). There is no need anymore for FLAGS_RESERVED if we use NR_PAGEFLAGS. Use the new methods to make NR_PAGEFLAGS available via the preprocessor. NR_PAGEFLAGS is used to calculate field boundaries in the page flags fields. These field widths have to be available to the preprocessor. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: David Miller <davem@davemloft.net> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pageflags: use an enum for the flagsChristoph Lameter2008-04-281-30/+26
| | | | | | | | | | | | | | | Use an enum to ease the maintenance of page flags. This is going to change the numbering from 0 to 18. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* MM: Fix macro argument substitution in PageHead() and PageTail()David Howells2008-02-211-2/+2
| | | | | | | | Fix macro argument substitution in PageHead() and PageTail() - 'page' should have brackets surrounding it (commit 6d7779538f765963ced45a3fa4bed7ba8d2c277d). Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix PageUptodate data raceNick Piggin2008-02-051-3/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After running SetPageUptodate, preceeding stores to the page contents to actually bring it uptodate may not be ordered with the store to set the page uptodate. Therefore, another CPU which checks PageUptodate is true, then reads the page contents can get stale data. Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after PageUptodate. Many places that test PageUptodate, do so with the page locked, and this would be enough to ensure memory ordering in those places if SetPageUptodate were only called while the page is locked. Unfortunately that is not always the case for some filesystems, but it could be an idea for the future. Also bring the handling of anonymous page uptodateness in line with that of file backed page management, by marking anon pages as uptodate when they _are_ uptodate, rather than when our implementation requires that they be marked as such. Doing allows us to get rid of the smp_wmb's in the page copying functions, which were especially added for anonymous pages for an analogous memory ordering problem. Both file and anonymous pages are handled with the same barriers. FAQ: Q. Why not do this in flush_dcache_page? A. Firstly, flush_dcache_page handles only one side (the smb side) of the ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away memory barriers in a completely unrelated function is nasty; at least in the PageUptodate macros, they are located together with (half) the operations involved in the ordering. Thirdly, the smp_wmb is only required when first bringing the page uptodate, wheras flush_dcache_page should be called each time it is written to through the kernel mapping. It is logically the wrong place to put it. Q. Why does this increase my text size / reduce my performance / etc. A. Because it is adding the necessary instructions to eliminate the data-race. Q. Can it be improved? A. Yes, eg. if you were to create a rule that all SetPageUptodate operations run under the page lock, we could avoid the smp_rmb places where PageUptodate is queried under the page lock. Requires audit of all filesystems and at least some would need reworking. That's great you're interested, I'm eagerly awaiting your patches. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* move page writeback acounting out of macrosAndrew Morton2007-07-191-30/+8
| | | | | | | | | | | | page-writeback accounting is presently performed in the page-flags macros. This is inconsistent and a bit ugly and makes it awkward to implement per-backing_dev under-writeback page accounting. So move this accounting down to the callsite(s). Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: share PG_readahead and PG_reclaimFengguang Wu2007-07-191-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Share the same page flag bit for PG_readahead and PG_reclaim. One is used only on file reads, another is only for emergency writes. One is used mostly for fresh/young pages, another is for old pages. Combinations of possible interactions are: a) clear PG_reclaim => implicit clear of PG_readahead it will delay an asynchronous readahead into a synchronous one it actually does _good_ for readahead: the pages will be reclaimed soon, it's readahead thrashing! in this case, synchronous readahead makes more sense. b) clear PG_readahead => implicit clear of PG_reclaim one(and only one) page will not be reclaimed in time it can be avoided by checking PageWriteback(page) in readahead first c) set PG_reclaim => implicit set of PG_readahead will confuse readahead and make it restart the size rampup process it's a trivial problem, and can mostly be avoided by checking PageWriteback(page) first in readahead d) set PG_readahead => implicit set of PG_reclaim PG_readahead will never be set on already cached pages. PG_reclaim will always be cleared on dirtying a page. so not a problem. In summary, a) we get better behavior b,d) possible interactions can be avoided c) racy condition exists that might affect readahead, but the chance is _really_ low, and the hurt on readahead is trivial. Compound pages also use PG_reclaim, but for now they do not interact with reclaim/readahead code. Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* readahead: introduce PG_readaheadFengguang Wu2007-07-191-0/+5
| | | | | | | | | | | | | | | Introduce a new page flag: PG_readahead. It acts as a look-ahead mark, which tells the page reader: Hey, it's time to invoke the read-ahead logic. For the sake of I/O pipelining, don't wait until it runs out of cached pages! Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Steven Pratt <slpratt@austin.ibm.com> Cc: Ram Pai <linuxram@us.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* xen: add pinned page flagJeremy Fitzhardinge2007-07-181-0/+5
| | | | | | | | Add a new definition for PG_owner_priv_1 to define PG_pinned on Xen pagetable pages. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
* mm: remove unused page flagsRafael J. Wysocki2007-05-071-12/+0
| | | | | | | | | | Remove the two page flags that were previously used by swsusp and are no longer needed. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: optimize compound_head() by avoiding a shared page flagChristoph Lameter2007-05-071-11/+26
| | | | | | | | | | The patch adds PageTail(page) and PageHead(page) to check if a page is the head or the tail of a compound page. This is done by masking the two bits describing the state of a compound page and then comparing them. So one comparision and a branch instead of two bit checks and two branches. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Make page->private usable in compound pagesChristoph Lameter2007-05-071-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we add a new flag so that we can distinguish between the first page and the tail pages then we can avoid to use page->private in the first page. page->private == page for the first page, so there is no real information in there. Freeing up page->private makes the use of compound pages more transparent. They become more usable like real pages. Right now we have to be careful f.e. if we are going beyond PAGE_SIZE allocations in the slab on i386 because we can then no longer use the private field. This is one of the issues that cause us not to support debugging for page size slabs in SLAB. Having page->private available for SLUB would allow more meta information in the page struct. I can probably avoid the 16 bit ints that I have in there right now. Also if page->private is available then a compound page may be equipped with buffer heads. This may free up the way for filesystems to support larger blocks than page size. We add PageTail as an alias of PageReclaim. Compound pages cannot currently be reclaimed. Because of the alias one needs to check PageCompound first. The RFC for the this approach was discussed at http://marc.info/?t=117574302800001&r=1&w=2 [nacc@us.ibm.com: fix hugetlbfs] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [S390] split page_test_and_clear_dirty.Martin Schwidefsky2007-04-271-1/+1
| | | | | | | | | | | | | The page_test_and_clear_dirty primitive really consists of two operations, page_test_dirty and the page_clear_dirty. The combination of the two is not an atomic operation, so it makes more sense to have two separate operations instead of one. In addition to the improved readability of the s390 version of SetPageUptodate, it now avoids the page_test_dirty operation which is an insert-storage-key-extended (iske) instruction which is an expensive operation. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [PATCH] Rename PG_checked to PG_owner_priv_1Nick Piggin2007-03-011-1/+3
| | | | | | | | | | | | Rename PG_checked to PG_owner_priv_1 to reflect its availablilty as a private flag for use by the owner/allocator of the page. In the case of pagecache pages (which might be considered to be owned by the mm), filesystems may use the flag. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* VM: Remove "clear_page_dirty()" and "test_clear_page_dirty()" functionsLinus Torvalds2006-12-211-6/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | They were horribly easy to mis-use because of their tempting naming, and they also did way more than any users of them generally wanted them to do. A dirty page can become clean under two circumstances: (a) when we write it out. We have "clear_page_dirty_for_io()" for this, and that function remains unchanged. In the "for IO" case it is not sufficient to just clear the dirty bit, you also have to mark the page as being under writeback etc. (b) when we actually remove a page due to it becoming inaccessible to users, notably because it was truncate()'d away or the file (or metadata) no longer exists, and we thus want to cancel any outstanding dirty state. For the (b) case, we now introduce "cancel_dirty_page()", which only touches the page state itself, and verifies that the page is not mapped (since cancelling writes on a mapped page would be actively wrong as it is still accessible to users). Some filesystems need to be fixed up for this: CIFS, FUSE, JFS, ReiserFS, XFS all use the old confusing functions, and will be fixed separately in subsequent commits (with some of them just removing the offending logic, and others using clear_page_dirty_for_io()). This was confirmed by Martin Michlmayr to fix the apt database corruption on ARM. Cc: Martin Michlmayr <tbm@cyrius.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrei Popa <andrei.popa@i-neo.ro> Cc: Andrew Morton <akpm@osdl.org> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] convert s390 page handling macros to functionsHeiko Carstens2006-09-291-6/+5
| | | | | | | | | | | | Convert s390 page handling macros to functions. In particular this fixes a problem with s390's SetPageUptodate macro which uses its input parameter twice which again can cause subtle bugs. [akpm@osdl.org: build fix] Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] update some mm/ commentsNick Piggin2006-09-261-15/+20
| | | | | | | | Let's try to keep mm/ comments more useful and up to date. This is a start. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] zoned vm counters: conversion of nr_writeback to per zone counterChristoph Lameter2006-06-301-4/+4
| | | | | | | | | | | | | Conversion of nr_writeback to per zone counter. This removes the last page_state counter from arch/i386/mm/pgtable.c so we drop the page_state from there. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] zoned vm counters: create vmstat.c/.h from page_alloc.c/.hChristoph Lameter2006-06-301-133/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | NOTE: ZVC are *not* the lightweight event counters. ZVCs are reliable whereas event counters do not need to be. Zone based VM statistics are necessary to be able to determine what the state of memory in one zone is. In a NUMA system this can be helpful for local reclaim and other memory optimizations that may be able to shift VM load in order to get more balanced memory use. It is also useful to know how the computing load affects the memory allocations on various zones. This patchset allows the retrieval of that data from userspace. The patchset introduces a framework for counters that is a cross between the existing page_stats --which are simply global counters split per cpu-- and the approach of deferred incremental updates implemented for nr_pagecache. Small per cpu 8 bit counters are added to struct zone. If the counter exceeds certain thresholds then the counters are accumulated in an array of atomic_long in the zone and in a global array that sums up all zone values. The small 8 bit counters are next to the per cpu page pointers and so they will be in high in the cpu cache when pages are allocated and freed. Access to VM counter information for a zone and for the whole machine is then possible by simply indexing an array (Thanks to Nick Piggin for pointing out that approach). The access to the total number of pages of various types does no longer require the summing up of all per cpu counters. Benefits of this patchset right now: - Ability for UP and SMP configuration to determine how memory is balanced between the DMA, NORMAL and HIGHMEM zones. - loops over all processors are avoided in writeback and reclaim paths. We can avoid caching the writeback information because the needed information is directly accessible. - Special handling for nr_pagecache removed. - zone_reclaim_interval vanishes since VM stats can now determine when it is worth to do local reclaim. - Fast inline per node page state determination. - Accurate counters in /sys/devices/system/node/node*/meminfo. Current counters are counting simply which processor allocated a page somewhere and guestimate based on that. So the counters were not useful to show the actual distribution of page use on a specific zone. - The swap_prefetch patch requires per node statistics in order to figure out when processors of a node can prefetch. This patch provides some of the needed numbers. - Detailed VM counters available in more /proc and /sys status files. References to earlier discussions: V1 http://marc.theaimsgroup.com/?l=linux-kernel&m=113511649910826&w=2 V2 http://marc.theaimsgroup.com/?l=linux-kernel&m=114980851924230&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115014697910351&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767318740&w=2 Performance tests with AIM7 did not show any regressions. Seems to be a tad faster even. Tested on ia64/NUMA. Builds fine on i386, SMP / UP. Includes fixes for s390/arm/uml arch code. This patch: Move counter code from page_alloc.c/page-flags.h to vmstat.c/h. Create vmstat.c/vmstat.h by separating the counter code and the proc functions. Move the vm_stat_text array before zoneinfo_show. [akpm@osdl.org: s390 build fix] [akpm@osdl.org: HOTPLUG_CPU build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] PG_uncached is ia64 onlyAndrew Morton2006-06-231-1/+13
| | | | | | | | | | | | | | As Nick points out, only ia64 uses PG_uncached. So we can push it up into the higher bits of the lower half of page->flags and make room for another flag on 32-bit machines. Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Jesse Barnes <jbarnes@sgi.com> Cc: Jes Sorensen <jes@trained-monkey.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] page flags: add commentry regarding field reservationAndy Whitcroft2006-04-111-2/+14
| | | | | | | | | | | Add some documentation regarding the utilisation of the flags field in struct page. This field is overloaded for per page bits and to hold node, zone and SPARSEMEM information. Make it clear which areas are used for what and how many bits are in each area. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix buddy list race that could lead to page lru list corruptionsNick Piggin2006-04-101-1/+7
| | | | | | | | | | | | | | | | | | | Rohit found an obscure bug causing buddy list corruption. page_is_buddy is using a non-atomic test (PagePrivate && page_count == 0) to determine whether or not a free page's buddy is itself free and in the buddy lists. Each of the conjuncts may be true at different times due to unrelated conditions, so the non-atomic page_is_buddy test may find each conjunct to be true even if they were not both true at the same time (ie. the page was not on the buddy lists). Signed-off-by: Martin Bligh <mbligh@google.com> Signed-off-by: Rohit Seth <rohitseth@google.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: page_state comment moreNick Piggin2006-03-221-2/+3
| | | | | | | | | Clarify that preemption needs to be guarded against with the __xxx_page_state functions. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: slab less atomicsNick Piggin2006-03-221-4/+2
| | | | | | | | Atomic operation removal from slab Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: page_alloc less atomicsNick Piggin2006-03-221-2/+2
| | | | | | | | More atomic operation removal from page allocator Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: less atomic opsNick Piggin2006-03-221-0/+2
| | | | | | | | | | In the page release paths, we can be sure that nobody will mess with our page->flags because the refcount has dropped to 0. So no need for atomic operations here. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: PageActive no testsetNick Piggin2006-03-221-2/+0
| | | | | | | | | PG_active is protected by zone->lru_lock, it does not need TestSet/TestClear operations. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: PageLRU no testsetNick Piggin2006-03-221-3/+2
| | | | | | | | | PG_lru is protected by zone->lru_lock. It does not need TestSet/TestClear operations. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: page_state opt docsNick Piggin2006-01-061-1/+11
| | | | | | | | Comment the new locking rules for page_state statistics. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: page_state optNick Piggin2006-01-061-11/+32
| | | | | | | | | | | | | | Optimise page_state manipulations by introducing interrupt unsafe accessors to page_state fields. Callers must provide their own locking (either disable interrupts or not update from interrupt context). Switch over the hot callsites that can easily be moved under interrupts off sections. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: dma32 zone statisticsNick Piggin2006-01-061-14/+24
| | | | | | | | | | Add dma32 to zone statistics. Also attempt to arrange struct page_state a bit better (visually). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] unpaged: unifdefed PageCompoundHugh Dickins2005-11-221-4/+0
| | | | | | | | | | | | | | | | | It looks like snd_xxx is not the only nopage to be using PageReserved as a way of holding a high-order page together: which no longer works, but is masked by our failure to free from VM_RESERVED areas. We cannot fix that bug without first substituting another way to hold the high-order page together, while farming out the 0-order pages from within it. That's just what PageCompound is designed for, but it's been kept under CONFIG_HUGETLB_PAGE. Remove the #ifdefs: which saves some space (out- of-line put_page), doesn't slow down what most needs to be fast (already using hugetlb), and unifies the way we handle high-order pages. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] VM: add page_state info to per-node meminfoMartin Hicks2005-09-051-0/+1
| | | | | | | | | | | | | | | Add page_state info to the per-node meminfo file in sysfs. This is mostly just for informational purposes. The lack of this information was brought up recently during a discussion regarding pagecache clearing, and I put this patch together to test out one of the suggestions. It seems like interesting info to have, so I'm submitting the patch. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: remove atomicNick Piggin2005-09-051-0/+1
| | | | | | | | | This bitop does not need to be atomic because it is performed when there will be no references to the page (ie. the page is being freed). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] __read_page_state(): pass unsigned long instead of unsignedBenjamin LaHaise2005-06-211-1/+1
| | | | | | | | | | By making the offset argument of __read_page_state an unsigned long instead of unsigned, we can avoid forcing the compiler to sign extend a usually constant argument. This saves 1 instruction on x86-64. Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] __mod_page_state(): pass unsigned long instead of unsignedBenjamin LaHaise2005-06-211-1/+1
| | | | | | | | | | By making the offset argument of __mod_page_state an unsigned long instead of unsigned, we can avoid forcing the compiler to sign extend a usually constant argument. This saves 1 instruction on x86-64. Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: remove PG_highmemBadari Pulavarty2005-06-211-16/+15
| | | | | | | | | Remove PG_highmem, to save a page flag. Use is_highmem() instead. It'll generate a little more code, but we don't use PageHigheMem() in many places. Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] count bounce buffer pages in vmstatKAMEZAWA Hiroyuki2005-05-011-0/+1
| | | | | | | | | | | | | | This is a patch for counting the number of pages for bounce buffers. It's shown in /proc/vmstat. Currently, the number of bounce pages are not counted anywhere. So, if there are many bounce pages, it seems that there are leaked pages. And it's difficult for a user to imagine the usage of bounce pages. So, it's meaningful to show # of bouce pages. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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